Do not double add BaseCommands in RootCommand children #439

Also register command aliases more completely

core/src/main/java/co/aikar/commands/BaseCommand.java

@@ -263,6 +263,7 @@ public abstract class BaseCommand {
             Collections.addAll(cmdList, cmdAliases);
             cmdList.remove(cmd);
             for (String cmdAlias : cmdList) {
+                registerSubclasses(cmdAlias);
                 register(cmdAlias, this);
             }
         }

core/src/main/java/co/aikar/commands/RootCommand.java

@@ -48,7 +48,9 @@ public interface RootCommand {
             subCommands.put(e.getKey(), e.getValue());
         });
 
-        children.add(command);
+        if (!children.contains(command)) {
+            children.add(command);
+        }
     }
 
     /**